The overall goal of this core is to conduct studies aimed at defining the effects of chronic low-level pesticide exposure on neurobehavioral development in mice. The Behavioral Toxicology Core will provide services for two research projects, one involving pre-natal exposure to pesticides, and the other early postnatal exposure. The Core will provide the capability of evaluating the functional development of the central nervous system, through the use of a Developmental Neurotoxicity Test Battery. This test battery includes measures of motor coordination, reflex responses, nociception, learning and memory, and the appearance of developmental landmarks in mice. The exact tests to be used for the Genetic Susceptibility study will be determined by the results obtained with the PON1-/- and PON1+/+ mice in the current period of support. For example, there were significant differences among treatment groups in the Morris water maze and open field tests (see progress report for the PON1 Polymorphisms study). Thus, tests which are determined by the current studies not to be affected by OP exposure (e. g., possibly the rotarod and radial arm maze tests) might be replaced by other behavioral tests, such as the platform reversal or delayed-matching-to- sample variants of the Morris water maze or a variant of the open field test that examines response to a novel object. The decision of which tests to include in the battery will hinge on the results obtained with the mice currently under neurobehavioral assessment. The Neurobehavioral Assessment Facility is a specific pathogen free (SPF) laboratory located on the fifth floor of the Health Sciences Building, close to the central animal facility and to several of the Center investigator laboratories. The facility is comprised of three rooms (273 sq ft, 78 sq ft and 53 sq ft), with space for housing up to 25 cages of SPF mice. The Department of Comparative Medicine's central facility, located just upstairs from the Behavioral Toxicology Facility, is an AAALAC-accredited SPF facility that has ample space for mouse housing. The Neurobehavioral Assessment Facility was first established in the current funding period to address the specific aims of the Center. Into the early part of 2001, an abnormally high neonatal mortality rate had been preventing expansion of the colony to a size large enough to begin behavioral testing. This difficulty was overcome by moving the mouse housing rooms and behavioral testing laboratory from an off-campus building to the Health Sciences Building, and by implementing SPF procedures in these rooms. This strategy has eliminated the high neonatal mortality that the investigators had been struggling with at the off-campus facility, and has the added advantage of placing the Neurobehavioral Toxicology Facility near the other Center laboratories in the Health Sciences Building. The facility was inspected and approved by the UW IACUC and veterinary services on January 2,2002. Behavioral studies commenced immediately after approval.